Here's why:

* Exothermic Reactions: These reactions release heat into the surroundings, causing the temperature to rise. Examples include combustion (burning) and the reaction of sodium with water.

* Endothermic Reactions: These reactions absorb heat from the surroundings, causing the temperature to drop. Examples include the dissolving of ammonium nitrate in water and photosynthesis.

So, chemical changes can be either:

* Exothermic: Heat is released (temperature increases).

* Endothermic: Heat is absorbed (temperature decreases).

Therefore, a chemical change producing heat is only true for exothermic reactions.